Any one out there with a duramax tahoe running a trans tune ? If so who did it for you and how was the experience ? I'm going through the proccess right now and I'm finding it hard to have confidence in the phrase "custom tune". Seems more like a generic truck tune than custom and requests for changes have initiated some odd responses. Just looking for some feedback from the experiences of others on how this procces goes with various tuners.
Duramax Tahoe. Tuning the allison 5 speed
- Thread starter gearguts
- Start date
What are wanting from the trans tune? Not much to be done in there besides shift points, TCc lock up and it’s lock/unlock points.
Yeah there's more to it than you would think. The truck tune is way off, the shifts are spaced too far apart and let the rpm come up too fast. I easily get into that defuel mode when everything just stops and you have to wait for it to come back and then try again. The passing gear downshifts are two gears. It's scary there's no need for that, and again the defuel thing has caught me here before as well. Anytime I'm slowing down theres no engine braking it just coasts along until you hit the gas again and then it slams into the wrong gear and has to shift immediately. Rpm's are just way too high in general and theres really nothing about the stock tune that works well with a vehicle that's so light. It's a 2001 5 speed so maybe not the same as other years ? It definitely got worse as I tried different tunes on the motor, with some it was almost undriveable.
Depending on what you have, You may need a differential regear along with a transmission tune. I would run a tighter converter too but that's just me. But, just getting the tune sorted out may make all the difference
Are you having someone else tune it or trying yourself?
Are you having someone else tune it or trying yourself?
Yes there's lots to screw with in the TCM, but what James is getting at, is that aside from the things he listed you shouldn't be messing with.
Half of your issues sound like a crappy engine tune. I'm sure your Tahoe isn't any lighter than a reg cab Dmax and they shift just fine.
I'd start with a 100% stock tune in both the ECM / TCM. If it doesn't shift decent stock, start looking elsewhere for issues
i know more about the inside of that TCM/tune than i care to.
as its been said, put a 100% stock 01 tune in the tcm and ecm. if it still acts up, its not a tune issue. either you have a speedo issue, fueling issue (it will cause it to rev out and not shift), or some wiring issues.
what year is your tahoe.
I owned and drove both the donor one ton and the tahoe for years before the conversion, both 2001. very familiar with stock tune. Ecm and tcm. There is no problem with the vehicle this is strictly tuning related. What defines a custom tune ? To me custom means custom to my vehicle and its specific requirements. How is this determined ? I would have expected to complete some forms and fill out some info about what I would like and how and when I would like it. And then once a tune is generated there would be a fine tuning process to dial it in. I would never expect anyone to get it right first try but as a tuner is it somewhat offensive if someone keeps asking for changes ? I feel like i was given a tune that should be "good enough" and that my requests for changes keep instgating a "there must be something wrong with your vehicle" statement. Just looking for other experinces with the tuning process.
Like other members have said, put the OEM 01 tunes back into the TCM and ECM. If it shifts great you now know the tuning is the issue. I also agree with others that your Tahoe is likely similar in weight to a reg cab long box and they do not have issues at all in regards to OEM shift strategy. Who knows, it is very possible that you do have an issue. The only way to actually know is to start doing some investigation as opposed to speculating on the forum. If the tuning is in question the very first thing I would do is start with the OEM untouched files.
As for custom vs "one size fits all", I'll be real honest with ya, tuners have spent hundreds of hours on their base/initial files. For 99.99999% of trucks the actual tuning part is all the same as they've been ironed out for ages. Those base files definitely do get revised/changed when a new methodology works better than what used to be done etc but realistically you're buying a file that someone has spent loads and loads of time to perfect the base mapping. Where you separate a mediocre tuner from a good one is on the custom side and revising files to meet a trucks needs for bigger injectors, turbos etc. IE if I have a library of tunes and just slap the same "max effort stock fuel/air" tune in every truck it'll likely run halfway decent but if your truck isn't meeting desired rail or isn't 100% following my desired boost curve then I need to determine why it isn't and how to make it do it and that is where a good tuner is able to overcome the truck's shortcomings vs a mediocre tuner just saying "it is what it is". Disclaimer, I am in no means an actual tuner, just my experiences.
because what you are wanting cant be fixed in the tune. again, what i posted is the extent of what will be done in a tcm tune and if that doesnt fix it, its not a tune issue. The tuner is not going to be your mechanic to fix what ever issue is going on. he can only work with what is supplied.
post a log of the truck doing all the issues you are saying and then elaborate at which part in the log the issue occurs.
you need to open up to the possibility there is a hard part or wiring issue here. if you cant be open minded, we cant help you
no tunes, put everything stock and log from there.
Before you go doing ANYTHING! Check what operating system is currently in your ECM. It is common practice to put an 02 OS in an 01 because the 01 OS is not mapped out the best, and is known to have many "ghost issues" when tuning. If your 01 was flashed to an 02, best case scenario flashing it back to stock 01 will corrupt your change engine oil counter making it always say to change your oil(this is documented in the efilive literature). More often than not it will brick your ecm(welcome to 01 lb7 life). And whatever you do, DO NOT flash it with a TECH 2 or anything using tis to go back to stock.
If it was mine, I would full flash in a 6006 02 OS with a V2, and use that for your base. For the TCM, flash it to the latest 01 OS completely stock. There are MANY MANY tables that EFILIVE put in there that should not be there. And messing with the trans tuning, even SMALL changes are a sure fire way to screw up your trans. Don't mess with the tire size or gear ratio settings, only changes to shift points, and I wouldn't touch any shift timing tables unless you're prepared to buy expensive hard parts when they get broken. And like most here are telling you, the bulk of your trans tuning is done in your ecm tuning.
If it was mine, I would full flash in a 6006 02 OS with a V2, and use that for your base. For the TCM, flash it to the latest 01 OS completely stock. There are MANY MANY tables that EFILIVE put in there that should not be there. And messing with the trans tuning, even SMALL changes are a sure fire way to screw up your trans. Don't mess with the tire size or gear ratio settings, only changes to shift points, and I wouldn't touch any shift timing tables unless you're prepared to buy expensive hard parts when they get broken. And like most here are telling you, the bulk of your trans tuning is done in your ecm tuning.
Alright I returned it too stock tuning for a couple days. Drives just the way I remember it. Not bad but too much like a big Flat deck one ton truck. The Tahoe is small and almost sporty.... this stock tune is not. So since I have the auto cal for a couple days I figured I would try to sort this out and build my own TCM tune. I pretty much got it where I like it changing only the shift point tables and the tcc apply and release. Lower rpms when putting around town but ready to go when you step on it, but not too ready... only one gear drop plus tcc unlock. So far so good. I'm tempted to copy and paste the "tow/haul" shift timing values into the "normal" tables to see if it will shift a bit quicker. Has anyone tried this ? I also notice that my shift points are very close to the "hot transmission" values, possible copy paste swap potential there. Figures, I noticed when I was nearly done. Only problem I have now is uploading the data log, file extension not allowed ?
Not sure about the operating systems on this truck, I'm sure they are probably the 01 originals. the ECM is 15188873 and the TCM is 15175854. Havn't had any problems so far.."knock on wood" Glad to hear anything you have to offer Thefermanator, your posts from years ago on this conversion topic are what got me started down this rabbit hole ....
Not sure about the operating systems on this truck, I'm sure they are probably the 01 originals. the ECM is 15188873 and the TCM is 15175854. Havn't had any problems so far.."knock on wood" Glad to hear anything you have to offer Thefermanator, your posts from years ago on this conversion topic are what got me started down this rabbit hole ....
I would not touch the shift timing. If it is not shifting fast enough it is likely the ECM tune and not the TCM. The amount of fuel pulled during a shift will make the transmission shift faster or slower or not at all if it is way off
Attached are two data logs. The one named "stock" is as you would guess, 100% factory tuning ecm and tcm. Just a short drive down the highway and up a side road. The second tune called "test 3" is my current trans tune and my current ecm tune, same drive. There's nothing wrong with the truck as far as I can tell and I was able to make a tune that I like. I didn't want to though, I would rather the $200 bucks I spent with a four letter tuner that we all know acheived the same results. Now I feel like I wasted my money, unless you guys can see a glaringly obvious problem I'd have to say I'm an unsatisfied customer.
I don't have any shifting "issues" either. This is the problem, I'm having. I don't like the stock shifting, I wanted a custom tune that will work with the way "I" drive. Instead I'm told over and over there is something wrong with my truck and the tune I got should be fine. Sure it might be fine for someone, but its not custom to my needs. Bottom line is I got screwed, i was told it would be no problem so I paid to have a custom tune made. All the while wondering how they were going to do this and what the process should be like. I expected to answer alot of questions or fill out some sort of build sheet that included some info on what I was looking for. Instead I just got a generic tune that IMHO would be great for a truck. The process of tweaking it too my liking has soured my opinion of the tuner I choose. How do other tuners do this ? This is my question, we've gone off track here. There's nothing wrong with my truck. And yes I recently developed an idle lope but this trans stuff was going on weeks ago so not an issue applicable to this thread.
I am going to go on a limb here and guess, because I have no idea who you used, but I am going to say that your issues are both yours and the tuners fault. Tuners don't always get it right and it is up to you to let them know. It is also no different than purchasing a product at a store thinking it will do what you want only to find out that it was less then impressive. You may need to shop around to find the one that works for you or take it up with the manufacturer. In your case, you will either press the tuner to provide what you paid for or move on. Maybe your expectations for what was being provided was wrong but in my opinion $200 for tuning is not going to get you much.
I would say be happy with what you have and consider it a learning experience. We here are not too fond of people constantly bad-mouthing or complaining. It fills up the threads with useless posts. Unless a vendor or other has a habit of sub par service then I don't think it's going to do use any good to keep on about it
I would say be happy with what you have and consider it a learning experience. We here are not too fond of people constantly bad-mouthing or complaining. It fills up the threads with useless posts. Unless a vendor or other has a habit of sub par service then I don't think it's going to do use any good to keep on about it